Many important cellular and biological processes are mediated by integral membrane proteins. Often quantities of these integral membrane proteins are required to study their roles in the critical cellular and biological processes. However, integral membrane proteins are often difficult to obtain in quantity while retaining solubility and function.
For example, according to one common technique, the integral membrane protein is extracted from the bilayer with a nonionic detergent. Unfortunately, the proteins recovered by such extraction techniques frequently lack activity.
In another common technique, a soluble portion of the membrane protein, such as an extracellular domain, is expressed in the absence of the insoluble portions of the membrane protein (typically the transmembrane region). However, this method is inadequate for expressing the soluble portions of many membrane proteins, especially those that traverse the membrane more than once. In such proteins that span the membrane more than once, the transmembrane domains and the lipid bilayer can be crucial to the proper folding of the soluble portion of the membrane protein.
New techniques are needed that provide quantities of integral membrane proteins, or domains or portions thereof, in a soluble and active form.